The bulk collection of phone “metadata” by the National Security Agency — records of who’s calling whom, when and for how long — is a potentially powerful tool that could, if abused, reveal sensitive facts about nearly every American’s life. The practice, disclosed by former NSA contractor Edward Snowden, demands extensive checks to guard against misuse. The government has said its oversight process is already strong. To varying degrees, a federal judge and a task force appointed by President Obama now have disagreed.

According to the Wall Street Journal, the task force, which was set to submit a sealed report to Obama over the weekend, would like to see a higher legal standard applied before the government can access phone records. It reportedly proposed an end to the bulk collection of records, instead calling on the NSA to approach phone companies and ask for records on a case-by-case basis. Government officials have seemed open to this but have voiced concern that investigative speed may be lost.

To make such a case, they will have to do better in demonstrating the national security benefit of the program. On Monday, U.S. District Judge Richard J. Leon signaled skepticism on that score as he issued an injunction to prevent the bulk collection. He stayed his action to give the government a chance to appeal, but ruled that the NSA, in maintaining a running five-year phone-records database, likely is in violation of the Constitution’s Fourth Amendment restrictions on unreasonable searches.

Rejecting the applicability of a 1979 ruling that offered no constitutional protections to metadata, Judge Leon argued that Americans’ relationship with technology has changed drastically now that cellphones and tablet computers are so ubiquitous and powerful. Moreover, he wrote, the government provided far too little evidence to show that its collection has proved valuable.